Propeller drive



Jan. 17, 1939.

F. W. CALDWELL PROPELLER DRIVE Filed May 19, '1936 2 Smets-Sheet l JAH/m11 v ATTORNEY Jan. 17, H93?.

` F. W. CALDWELL PROPELLER DRIVE .2 sheets-sheet 2 Filed May '19, 1936 A TT ORNEYS.

engaged at will. vThe propeller shaft Il is supported in the 15 V driving connection between the engineand proplane upon which the engine is mounted. 20 peller where the drive forces are at their mini- The propeller, generally indicated at 22, is mum value. a controllable pitch type well-#known to the art .25 the engine and the propeller to permit the proabout their longitudinal axes to change the pitch Patented Jan. 17, 1939 'c Y c 2,144A234 UNITED sTA'rEsc, PATENT OFFICE 'wormen Dmvn Frank W. Caldwell, Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application '19, 1936, Serial No. 80,551)

1 Claim. (CLIN- 162) This invention relates to improvements' in Fig. 3 is a side elevational view of the brake propeller drives `and particularly to a reasonable operating mechanism illustrated in Fig.`2.

drive for a controllable pitch aeronautical pro- Referring tol the drawings in detaiLthe nupeller.. meral I0 generally indicates an engine which 5 An object of the invention lies in the provimay be a radial internal combustion engine fre- 5 sion of a, releasabledrive of the character-speciquently used for the propulsion of aircraft, but ed whereby the driving connection between the within the scope of the invention may be any engine and the propeller may be released and other type of power plant suitable to drive an the propeller allowed to rotate without rotating aeronautical propeller. 10 the engine. p The engine illustrated has a fixed nose Por-l 10 A further object resides in the provision .of tion I2 through which extends a rotatable proa releasable propeller drive of the character peller drive shaftlt drivingly connected to the vspecified wherein the drive between the propeller engine power shaft or crankshaft I6 by a suitand the engine may be manually released or able reduction gearing generally indicated at I8.

A still further object resides in the provision nose section I2 by means of an anti-'friction ball of a releasable propeller drive of the character bearing 20 which'serves to center the propeller specified wherein the drive releasing and enshaftinthe nose section and also to transmit the gaglng means is applied to an element of the propeller thrust load to the engine and theair- An additional object resides in the provision and has its blades 24 rotatably mounted in the of a releasable connection in the drive between hub portion 26 so that the blades may be rotated peller to rotate freely or free wheel with respect angle thereof. The blades are moved in one to the engine so that the propeller drag .of a direction of rotation by a suitable hydraulic dead engine may be reduced to the minimum and mechanism, generally indicated at '28, and are the propeller prevented from rotating the engine moved in the opposite direction by centrifugallywhen in a defective condition, and also to preactuated counterweights 30, in the form of pro- 30 vent the propeller from over-revving an engine. peller illustrated the hydraulic mechanism being during a high velocity dive and permit the Ause used to move the blades toward their low pitch of a propeller as a brake to slow down the speed position and the counterweights 30 tending to of an airplane during a prolonged dive. vOther move the blades toward their high pitch position.

objects and advantages' will be more particularly A propeller of this type iS Particularly illustrated 35 pointed out hereinafter or will 4become apparent and described in Patent No. 2,032,255 issued as the description proceeds.` l February 25, 1936, to F. W. Caldwell. The lim- In the accompanying drawings wherein like iting low andhigh pitchpositions of the blades reference numerals are used to designate similar are dellitely determined by 8.9811' 0f .11111112 SISODS 40 parts throughout,'there is'illustrated what is now 29' 29' included in the connection between the 40 considered to be the preferred form of the idea. 'movable element 0f. the hydraulic mechanism 23 of the invention. The drawings, however, are and the' counterwelehts 39' If' for 91m/ reason f for the purpose of illustration only and are not seonligiesggegll ssfllplnl; lrxnplrlln E; :emkgtsblmnisgu grogg, l :ggghydraulic mechanism 28 would be relieved and 45 ofthe appended claim l the counterweights 30 would move the propeller In, the drawings Fig 1 is anelevtional View blades to their limiting high pitch position during the slowing down of the engine before it was com- 'of a propeller aj'fragment-ary portion of an en' pletely stopped or during free-wheeling of the g1ne, and the driving-connection between the enpr0peuer 50 gine and the Propeller' certain Demons being The shaft I4 is driven-from the power shaft .broken away. and 'Shown in Section t0 better vI6 through thel planetary reduction gear train 'illustrate the Construction thereofgenerally indicated at I8 as stated above. An

Fig. 2 -is a sectional view on the line 2-2 0f annular ring gear 32 is mounted upon the 'for- Fig. 1. ward end of the power shaft I6 by means of a 55 bell housing 34 secured upon the splined forward end of the drive shaft by means of a thrust nut 36 and centered with respect to the xed parts of the engine by means of a suitable anti-friction bearing 39. 'I'he annular drive gear 32 is provided internally thereof with gear teeth which mesh with the teeth of a plurality of planetary gears 38 mounted upon axles .40 carried by a cage 42 drivingly connected to the propeller shaft I4 by means of suitable locking splinesM. 'I'he cage is located axially upon the shaft |4 by means of a thrust nut 46 threadedupon a screw threaded portion of' the shaft I4 at the rear end of the cage 42 and which forces the cylindrical sleeve portion 48 of the cage which surrounds the splined portionof the shaft I4 against an oil collector ring 60 surrounding the shaft I4 between the forward end of the cage and an annular shoulder of a radial extension 52 provided upon the shaft H immediately rearwardly of the inner race of the bearing 20. The bearing is forced against the opposite annular shoulder of the extension 52 by a suitable thrust nut 56 screw threaded upon a screw threaded portion of the shaft I4 immediately forward of the bearing.

. The planetary gears also mesh with gear teeth provided upon a fixed sun gear 56 which is rotatably-supported upon a sleeve extension 50 of a xed member 60. 'Ihe member 60 is secured to the ixed nose portion I2 by means ,of the bolts 62 extendingthrough the xed memplanetary gears 38 will be rotated and caused to revolve about the sun gear, carrying with them the cage 42 so that the cage and the shaft I4 to which the cageis drivingly connected will be rotated at a speed less than the rotational speed of the drive gear 32 and the power .shaft I6.

If, on the other hand, the sun gear 58 is allowed4 to rotate freely, the planetary gears 38 will be caused to rotate but will not' impart any motion to the cage, since the only effect of their rota'- tion will be to rotate the sun gear. Also with the sun gear free' to rotate, the cage 42 may rotate without rotating the drive gear 32. From the relation of the partsit is also obvious that the force required to hold the sun gear fixed is less than the force exerted by the planetary gears upon the cage 42 or by the drive gear 32 upon the planetary gears. Therefore. the sun gear is inherently the easiest of the various gear elements to control.

In order to provide for holding the sun gear iixed or allowing it to rotate freely upon its bearing member 50, this sun gear is provided with a radial flange portion 66 connected at its outeredge to an annular portion, generally indicated at 68, which overlies the planetary gears 38 and a portion of the drive gear 32. A part 10 of the annular portions 60 is formed as a brake drum, and about this drum there is applied a flexible brake band 12. Another part, 14, of the annular portion 68 is formed as one portion of a dog clutch and is provided with a series of spaced notches or indentations 16 particularly illustratedin-Flg. 2, 4which notches receive the pin or lug portion 10 of a'suitable dog 80 for positively locking the sun gear in a iixed condition,

In accordance with the idea/of this invention, if the sun gear 66 were free and were rotating under the influence of a propeller rotation in excess of engine rotation and it were desired to bring the sun gear to a fixed condition, the, brake band 12 would first be applied to frictionally reduce the speed of the sun gear and bring it substantially to a stop, after which the dog member 80 would be actuated to force the lug 18 into one of the notches 16 to positively hold the gear in its fixed condition.

Suitable means have been illustrated for applying `the braking action of the brake band 12, but it is to be understood that the invention is in no way limited to the particular mechanism herein illustrated and described, as various forms of brake actuating mechanism could be utilized.

In the form of Vbrake actuating mechanism illustrated, a bifurcated lug member 62 is rigidly secured to the interior of the xed nose portion I2 by suitable means, such as cap screws 64. This member is provided with two inwardly extending lug portions indicated at 66 in Fig. 3. which extend upon opposite sides of the brake band 12 and are there apertured to receive a through pin 08. One end of the brake band 12 is anchored to the pin 88 as indicated at 00 in Fig. 3, and the dog member 00 is also pivotally supported upon the pin 06land is positioned in a slot or aperture 92 provided in the anchored end of the brake band. The opposite end of the brake band is secured, as indicated at 94, to one end of a loop member 96,\the opposite end of which is connected tolone element 9 8 of a screw mechanism,'the construction and purpose of which will be presently described. 'I'he loop member 96 is'provided intermediate its length with a cross bar |00 upon which toggle links |02 arepivotally mounted adjacent the ends of the cross bar, the opposite ends of the toggle links being secured to the pin 38 extending through the end 90 of the brake band.

From the above description it will be observed that a downward pull on the end of the loop member connected to the screw 98 wil1` move the vend 94V of the brake band toward the xed end 90 by reason of the decrease in angulai'ityV member is provided with a leaf spring |04 whichv extends under the cross bar |00 so that as the loop member 96 is moved downwardly the cross bar will ,come in contact with the upper surface of the spring and resiliently urge the lug 1li of the dog member 80 into one of the notches has been engaged to lock the sun gear. A por-A tion of the dog member extends beyond the.

mounting pin 08 on the side opposite the hookor lug portion 18 and is there provided with a cam |06 which bears against the movable end 94 of the brake band so that asthe dog'memberV is moved upwardly by the pin |06 thecam Ill will act against the end 94 of the brake band to move that end of the brake band away from the a sleeve ||6 and is maintained against axial movement with respect to the sleeve by means of a shoulder or ang'e H8 at one end thereof and a thrust nut |20 at the opposite end. The sleeve ||6 is secured to the inner wall of the xed nose section l2 by means of a suitable pivotal connection |22 arranged to allow a limited tilting movement of the'entire screw mechanism so that the end of the screw 98 can follow the end of the loop member 96 without undue resistance.

From the above description it will be observed that the operator of the airplane may lock vor release the sun gear 56 by manual' operation of the crank ||4.Y .In locking the sun gear the action is to irst bring the rotating sun gear substantially to a stop by application of the brake band 12 and then to force the lug ofthe dog member 8|) into two of the notches 'I6 to positively retain the sun gear againstmovement. In releasing the sun gear the dog member 80 is first removed from its engagement in the notch 16 by the upward movement of the loop member 96 during which time the tension on the brake band 12 is only slightly decreased. After the latch member has been released, a further upward movement of the loop member releases the brake band and allows the sun gear to rotate freely so that the propeller may rotate freely with respect to the engine.

As stated above, the propeller 22 is a controllable pitch propeller operated in one direction by the action of centrifugal force upon the counterweights 30 and operated in the other direction by the introduction of hydraulic fluid under pressure into the hydraulicmechanism 28.

- The hydraulic iiuid is supplied to the hydraulic mechanism from a suitable source of pressure, such as an engine driven pump, and ows through a manually adjustable speed controlling governor |24.' From the governor the fluid ows through the-conduits |26 and |28 to the oil collector ring'50, the inner endl of the conduit |28 being anchored in the xed member'll. The oil collector ring is provided with oil seal rings" |30 and with an aperture |32 which extends from the end of the conduit 1| 28 between the oil seal rings |30 through the oil collector ring 50 and connects with a.. similar aperture |34 leading through the wall of the hollow shaft I4 to the interior of the'shaft. Adjacent to the inner end longed dive. imately 5 degrees has been found desirable for of the aperture |34, a plug |36 is mounted in 'the bore of the shaft I4 so that the hydraulic uid flowing into the shaft will be forced to iiow Athrough the forward portion of the hollow shaft to the hydraulic mechanism 28.

The movable propeller blades 24 are providedwith suitable limit stops which limit their rotational movement to a certain predetermined angular range. One of the stops is adjusted to provide the anglel of pitch adjustment most advantageous for reducing the drag of the propeller when permitted to rotate freely with respect to the engine. A high pitch settingiof approximately 50 degrees has been found to be useful for this purpose. 'I'he other stop may, if desired, bev adiusted to provide the most advantageous pitch angle for increasing the drag of the propeller Awhen allowed to rotate freely with respect to the engine, so that, if desired, the propeller may be used for a brake to slow down the speed of the airplane during landing or a pro- A low pitch setting of approxthe purposes indicated.

According to present ideas, the principal advantagel of the element resides in the fact that if one engine of a multi-engine airplaine is stopped either voluntarily or because of engine failure, the Aresistance of the propeller driven by l that engine may be reduced to a negligible value by allowing the propeller to rotate freely with respect to the engine at a relatively high pitch angle without, however, providing a range of pitch adjustment sufcient to place the propeller blades in a feathered condition.

While there has been illustrated and described a particular mechanical embodiment of the idea of the invention, it is to be understood that the invention is not limited to the particular mechanical embodiment so illustrated and described, but that such changes in the size, shape, and arrangement of parts may be resorted to as come within the scope of the appended claim.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows.

What isl claimed is:

In combination with a propeller driving engine and a controllable pitch propeller having .its blades rotatable for pitch changing adjustment within a range ofA pitch angles of from approximately fty degrees at highy pitch, means providing a manually releasable driving connection,A

' imately ve degrees-at low pitch to approx- 

